A te en­age girl has be­come the
wo rld’s first known trans­plant pa­tient to change blo od groups and take on the im­mune sys­tem of her or­gan do­nor, doc­tors in Aus­tral­ia said on Jan. 25, call­ing her a
“one-in-six-billion mir­a­cle.”

Demi-Lee Bren­nan, now 15, re­ceived a do­nor liv­er when she was 9 years old and her own liv­er failed.
“It’s like my sec­ond chance at life,” she told lo­cal me­dia, re­co unt­ing how her body achieved what doc­tors said was the holy grail of trans­plant sur­gery.
“It’s kind of hard to be­lieve.”

Bren­nan’s body changed blo od group from O neg­a­tive to O pos­i­tive when she be­came ill while on drugs to avoid re­jec­tion of the or­gan by her bod­y's im­mune sys­tem. Her new liv­er’s blood stem cells then in­vad­ed her bod­y's bone mar­row to take over her en­tire im­mune sys­tem, mean­ing the teen no long­er needs an­ti-re­jec­tion drugs.

Doc­tors from Syd­ney’s We st­mead Chil­drens’ Hos­pi­tal in
Australia said they had no ex­plana­t­ion for Bren­nan’s reco­very, de­tailed in the lat­est edi­tion of
The New Eng­land Jo ur­nal of Med­i­cine. “There was no prec­e­dent for this hav­ing hap­pened at any oth­er time, so we were sort of fly­ing by the seat of our
pants,” Mi­chael Stor­mon, a pe­di­at­ric hep­a­tol­o­gist, told lo­cal ra­dio.

Stu­art Dor­ney, the hos­pi­tal’s form­er tra ns­plant un­it head, said Bren­nan’s treat­ment could lead to break­throughs in or­gan trans­plant treat­ment, be­cause nor­mally the im­mune sys­tem of re­cip­i­ents at­tacked the trans­planted tis­sue.
“We now need to go back over eve­ry­thing that ha p­pened to Demi-Lee and see why, and if it can be repli­cat­ed,” said Dor­ney.

“We think be­cause we used a you ng per­son’s liv­er and Demi-Lee had low white blood cells, that could have been a rea­son,” he told the
Daily Tel­e­graph news­pa­per. Re­jec­tion is no r­mally treated with a com­bina­t­ion of drugs, al­though chron­ic re­jec­tion is ir­re­vers­i­ble. Only seven-in-10 trans­plant opera­t­ions in Aus­tral­ia are suc­cess­ful af­ter a five-year pe­ri­od due to re­jec­tion com­plica­t­ions.